With the rapid development of domestic wireless communication and IoT sensing technologies, a large number of housing, hotels, commercial buildings, and office buildings have begun their intelligent upgrades, and people are slowly adapting to a more intelligent daily work and life. Not only in civilian applications, IoT technology is also gradually integrating into the industrial field.
In the short-range wireless communication technologies for implementing IoT, Bluetooth, Wi-Fi, and Zigbee are currently the three most widely used short-range wireless communication technologies; while 4G, 5G, NB-IoT, Sigfox, and LoRa represent long-distance wireless transmission technologies.
Short-Distance Transmission Technologies
1. Bluetooth:
Bluetooth is a technology for wireless communication between devices, enabling short-distance data exchange between fixed devices, mobile devices, and personal area networks in buildings. Bluetooth can connect multiple devices, overcoming the challenges of data synchronization. Bluetooth uses short-wave high-frequency (UHF) radio waves to communicate in the 2.4 to 2.485 GHz ISM frequency band, with communication distances ranging from a few meters to hundreds of meters.
Advantages:
In “low-power Bluetooth” mode, it achieves low power consumption, enhanced coverage, with a maximum range exceeding 100 meters.
Supports complex networks: optimized for one-to-one connections and supports star topology for one-to-many connections.
Smart connectivity: increases support for setting connection frequencies between devices, supports IPv6 networks.
Higher security: uses AES-128 CCM encryption algorithm for packet encryption and authentication.
Bluetooth modules are very small and easy to integrate.
Can establish temporary peer-to-peer connections (Ad-hoc Connection): Bluetooth devices can be classified as master (Master) and slave (Slave) based on their roles in the network.
Disadvantages:
Incompatibility among various versions of Bluetooth, poor networking capability; few network nodes, not suitable for multi-point control.
2. Wi-Fi:
Wi-Fi is a wireless local area network communication technology, short for Wireless Fidelity. The IEEE organization has established the IEEE 802.11 standard for Ethernet technology. Wi-Fi terminals use high-frequency radio signals to send and receive data, employing Ethernet communication protocols, with communication distances typically in the tens of meters. The current standard has been updated to 802.11ax.
Advantages:
The advantage of Wi-Fi is that local area network deployment does not require the use of wires, reducing deployment and expansion costs. Additionally, according to the Wi-Fi Alliance, “Wi-Fi certification” is backward compatible, specifying a globally unified standard: unlike mobile phones, any Wi-Fi standard device will operate correctly anywhere in the world.
Disadvantages:
The disadvantages of Wi-Fi are limited communication distances, poor stability, high power consumption, poor networking capability, and inadequate security, making it ineffective for industrial applications.
Long-Distance Transmission Technologies
With the development of smart cities, one of the representatives of long-distance wireless transmission technologies is that traditional manual meter reading will be replaced by remote meter reading. Wireless remote meter reading not only addresses the drawbacks of manual meter reading but also reduces the operational management levels of power supply companies, improving work efficiency and lowering operational costs.
1. 4G and 5G applications in IoT – Outstanding representative Cat.1
Shared bicycles, mobile POS machines, etc., can be typical application scenarios for Cat.1. Compared to NB-IoT and 2G modules, Cat.1 has advantages in network coverage, speed, and latency. Additionally, Cat.1 has certain cost advantages; for example, LTE Cat.1 can seamlessly integrate into existing LTE networks without the need for hardware and software upgrades for base stations, resulting in low network coverage costs. In terms of chip costs, after system optimization, the integration is higher, the module’s hardware architecture is simpler, and peripheral hardware costs are lower. In terms of latency, it has millisecond-level transmission latency similar to LTE Cat.4 and supports speeds over 100KM/H.
However, it also faces similar issues as the development of NB-IoT; after all, the price of modules is key to rapid scaling. Currently, the price is still somewhat high, but it is believed that after some time, Cat.1 will experience robust growth.
2. LoRa
LoRa modulation: LoRa (Long Range) is a modulation technology that offers longer communication distances compared to similar technologies. The modulation is based on spread spectrum technology, a variant of linear modulation spread spectrum (CSS), with forward error correction (FEC). LoRa significantly improves receiving sensitivity, and like other spread spectrum technologies, it broadcasts a signal using the entire channel bandwidth, making it more robust against channel noise and frequency offsets caused by low-cost oscillators. LoRa can modulate signals 19.5 dB below the bottom noise, while most frequency shift keying (FSK) requires a signal power of 8-10 dB above the bottom noise to modulate correctly. LoRa modulation is at the physical layer (PHY) and can be used for different protocols and network architectures – Mesh, Star, point-to-point, etc.
LoRa terminals can form a self-organizing network, uploading data to the cloud platform through a concentrator, suitable for scenarios where terminals are dispersed and data processing is centralized. LoRa has strong penetration capabilities, with a wireless line-of-sight range of up to 3 kilometers. Each terminal equipped with a module can act as a relay point for remote terminals. No wiring is needed, installation is convenient, data transmission is stable, and measurement data can be monitored online. The remote system based on LoRa not only has advantages such as easy embedding, large networking capacity, low power consumption, and no fees, but also features high receiving sensitivity and strong wall-penetrating communication capabilities. The actual measured communication distance can exceed 3 kilometers, perfectly solving the problem of ultra-long-distance communication for small data volumes in complex environments.
All the aforementioned IoT wireless communication technologies aim to meet their respective communication needs in different scenarios:
1. High-power, high-speed wide area network transmission technologies, such as 4G and 5G cellular communication technologies, are suitable for high-volume transmission applications with real-time requirements, such as GPS navigation and video surveillance.
2. Low-power, low-speed wide area network transmission technologies, such as LoRa, Cat1, and NB-IoT, are suitable for data transmission of remote device operating statuses, industrial smart devices, and terminals.
3. High-power, high-speed short-distance transmission technologies, such as Wi-Fi and Bluetooth, are suitable for smart homes, wearable devices, and data transmission between M2M connections.
4. Low-power, low-speed short-distance transmission technologies, such as ZigBee, are suitable for flexible networking applications of local area network devices, such as hotspot sharing.
Currently, the development trend of IoT wireless transmission technologies is primarily focused on low-power wide area networks. It is expected that in the coming years, low-power wide area network transmission technologies represented by LoRa, Cat1, and NB-IoT will gradually become the mainstream connection technologies for IoT transmission layers.
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